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Summer is a great time for fun in the sun, but it can also be a time for uncomfortable heat rashes. Also known as prickly heat or miliaria, heat rashes can develop in hot, humid environments. Symptoms of summer heat rashes include red skin, little red bumps on your skin, tiny blisters, and a prickly or itchy feeling. Fortunately, you can treat summer heat rashes and even take steps to prevent them from developing in the first place.

The skin protects the inside of your body from the outside world. It acts as a preventive barrier against infection, chemicals, and dangerous ultraviolet (UV) rays from the sun.

Skin also plays a role in controlling body temperature. Special sweat glands located in skin all over the body produce sweat, which is liquid made of 99 percent water and 1 percent salt and fat. When body temperature rises, the sweat glands produce sweat; in a process known as evaporative cooling, air evaporates the sweat on the surface of the skin to cool the body.

Preventing & Treating Summer Heat Rashes
Heat rash can develop when something clogs the ducts that carry sweat from the glands to the surface of the skin. The clog traps the sweat beneath the skin’s surface, which triggers a mild inflammation or rash.

Adults typically develop heat rash in spots where clothing causes friction, and in the folds of their skin, such as the underarms, elbow creases, and groin. Infants usually develop heat rash on their neck, shoulders, and chest.

Newborns and infants, elderly adults, and obese individuals who have large areas of skin-on-skin contact are at risk for developing heat rash. This is particularly true if they are immobile for long periods and without enough circulating air to allow for evaporative cooling.

Types of heat rash

Medical professionals classify heat rash according to how deep within the skin the blocked sweat ducts are located. The signs and symptoms may be slightly different for each type of heat rash.

Miliaria crystalline

The mildest form of heat rash, known as miliaria crystalline, affects only those sweat ducts situated in the top layer of skin. It causes the formation of clear, fluid-filled bumps and blisters that leak and break easily.

Miliaria rubra

Also known as prickly heat, miliaria rubra occurs deeper in the skin. Signs and symptoms of this type of heat rash include red bumps and an itching or prickling sensation in the affected area.

Miliaria pustulosa

miliaria pustulosa can develop when the fluid-filled sacs of miliaria rubra fill with pus and become inflamed.

Miliaria profunda

Miliaria profunda is a less common form of heat rash that affects a deeper layer of skin, known as the dermis. Sweat leaks out of the sweat gland and into the skin to cause firm, flesh-colored lesions that look like goose bumps.

Treatment for Summer Heat Rashes

Cool skin
The first line of treatment for summer heat rashes is to get out of the heat; a mild heat rash should subside as the skin cools.

Apply cool compresses to the affected area
Apply a cool compress to lower the temperature of your skin. Let the moisture on your skin air dry to promote evaporative cooling.

More-severe forms for heat rashes may require ointments applied to the affected skin. Ointments many include calamine lotion to soothe itching, and anhydrous lanolin to prevent blockage of the ducts and the formation of new lesions. Topical steroids may be necessary in severe cases.

Prevention of Summer Heat Rashes

Dress to stay cool
Dress in loose-fitting, lightweight and breathable clothing that wicks moisture away from your skin. Your clothing should promote evaporative cooling rather than inhibit it.

Protect your skin from sunlight
Exposure to sunlight may trigger perspiration that causes heat rash. Sunlight can also cause sunburn that could worsen your symptoms of heat rash.

Use fans to promote evaporative cooling
When you start to sweat, turn on a fan to evaporate sweat before it irritates your skin.

Take advantage of AC on hot, humid days
Spend as much time as possible in air-conditioned environments on hot, humid days to avoid sweating.

Keep skin clean and cool
Take frequent baths or showers to keep skin cool; be sure to use non-drying soap. Baths and showers also help prevent sweat glands from clogging. Instead of toweling off, let the air dry your skin to promote evaporative cooling.

Avoid products that can block sweat ducts
Creams and ointments containing petroleum or mineral oil can block your sweat ducts to increase your risk of heat rashes.

Reduce areas of overlapping skin-on-skin
Losing weight can help reduce skin-on-skin contact, but even thin people can develop heat rashes where skin meets skin. To avoid heat rashes, avoid crossing your legs for long periods or sitting in positions that cause overlapping skin.

Take care of other skin problems
Heat rashes can worsen existing skin problems, such as eczema and psoriasis. To stay comfortable all summer long, take extra steps to keep all of your skin problems under control.

When to See a Doctor about Heat Rash

Heat rash usually subsides on its own or with home care. If these treatments do not work, or if they make the heat rash worse, see a dermatologist. A skin doctor can determine if your symptoms are the result of heat rash or another issue. Your dermatologist can also prescribe medications as necessary to alleviate symptoms.

For more information about the prevention and treatment of summer heat rashes, consult with your skin doctor at Center for Dermatology & Laser Surgery. Our dermatologists can diagnose and treat heat rash, and help you find more ways to enjoy fun in the sun without harming your skin.